The present invention relates to an electronic device mounting a plurality of electronic components (semiconductor device and capacitor) over a wiring substrate (mother board), for example.
An electronic device constituting an electronic circuit mounts a plurality of capacitors (capacitor elements) together with a semiconductor device.
Japanese Patent Laid-Open No. 2007-305642 (Patent Literature 1) discloses an electronic device mounting a microcomputer (corresponding to the above semiconductor device) on a principal surface of a multilayer circuit substrate (corresponding to a mounting substrate to be described below). The rear surface of the multilayer circuit substrate mounts a three-terminal capacitor for reducing unnecessary radiation noise, and an auxiliary capacitor (two-terminal capacitor or three-terminal capacitor) for suppressing voltage fluctuation. The microcomputer is electrically connected with the three-terminal capacitor and the auxiliary capacitor via a via-hole of the multilayer circuit substrate.
Japanese Patent Laid-Open No. 2011-249412 (Patent Literature 2) discloses an electronic device coupling a first three-terminal capacitor to a first wiring layer formed on a principal surface of a multilayer wiring substrate (corresponding to a mounting substrate to be described below), which is an IC (corresponding to a semiconductor device to be described below) mounting surface, and coupling a second three-terminal capacitor to a second wiring layer formed on the rear surface opposite to the principal surface. Input terminals of the first and second three-terminal capacitors are electrically connected with a power supply circuit, output terminals are electrically connected with a power supply terminal of IC, and ground terminals are electrically connected with a ground layer disposed between the first wiring layer and the second wiring layer of the multilayer wiring substrate and further to a ground terminal of IC via a via. Patent literature 2 describes that, since the first and second three-terminal capacitors are grounded in common, an electromagnetic compensation effect by noise flowing in the ground layer is caused, and ESL (Equivalent Series Inductance) is reduced and thus the noise is caused to flow easily in the ground layer.